1. Field of the Invention
The present invention relates to wallpaper for shielding electromagnetic waves and, more particularly, to wallpaper for shielding electromagnetic waves prepared by applying and coating onto the surface of raw paper, a coating composition which is composed of at least one material selected from the group consisting of a conductive polymer material having inherent resistance against electromagnetic waves, conductive carbon and graphite, and additives, mixed in a predetermined mixing ratio.
2. Description of the Related Art
As social concerns have recently grown increasingly about human health, research into the effects of various kinds of harmful waves on the human body and the methods of effectively shielding such harmful waves has been vigorously carried out. According to scientific research carried out hitherto, electromagnetic waves have been proven to be the most typical harmful waves.
A large amount of electromagnetic wave interference is emitted from electric wires and electric/electronic product, that have been in general use, such as home appliances, wireless communication devices, control devices, power systems, high-frequency equipment, lighting devices, electric heaters, microwave ovens and so on. Thus, it is no exaggeration to say that the electromagnetic waves are being emitted from all parts of the world. In recent years, the electromagnetic wave noise emitted from various digital systems including computers has been recognized as the most serious artificial noise source.
The general theory and adverse effect of electromagnetic waves will now be briefly described. Electromagnetic waves refer to waves generated while an electric field, formed by the intensity of charges, and a magnetic field, formed by the movement of charges, travel in phase with time. While the electric field is absorbed or shielded by conductive materials, the magnetic field has high transmissivity, that is, the magnetic field penetrates all kinds of materials. In particular, it is known that the magnetic field is much more hazardous to the human body than the electric field.
It is also known that the electromagnetic fields cause to a greater or lesser degree, various functional disorders in living tissue. Research efforts on the protection of the human body against the adverse effect of electromagnetic waves are actively underway.
A conventional means for shielding electromagnetic waves, that is, electromagnetic wave shielding wallpaper, will now be described by way of example.
FIG. 1 is a perspective view showing conventional wallpaper 10 for shielding electromagnetic waves.
As shown in FIG. 1, the conventional wallpaper 10 for shielding electromagnetic waves is prepared by adhering metal coated paper 16 to the back surface of raw paper 12 having a front and gravure printed surface, by means of an adhesive 14. Here, nickel (Ni) or copper (Cu) coated fabrics or nonwoven fabrics, that have been pre-treated, catalyzed and activated, can be used as the metal coated paper 16.
Alternatively, the conventional electromagnetic wave shielding wallpaper may be prepared by coating a solution of electromagnetic wave absorbent material on the entire surface of the front surface of raw paper and drying the resultant surface, foaming and applying a polyvinyl chloride (PVC) compound onto the entire surface of the electromagnetic wave absorbent layer to a predetermined thickness, coating an appropriate surfactant, which may vary according to use, and then performing conventional post-treatment. Here, the electromagnetic wave absorbent material comprises at least one of iron oxide (Fe2O3), nickel oxide (NiO), zinc oxide (ZnO) and copper oxide (CuO) as the main component, a dispersing agent and a lubricator. The PVC compound comprises PVC, dioctylphosphate, a stabilizer, a foaming agent, TiO2, and a filler, e.g., CaCO3.
However, since the conventional electromagnetic wave shielding wallpaper is quite difficult to manufacture, improvement in the productivity thereof cannot be expected. Also, since metal is employed as an electromagnetic wave shielding material, the manufacturing cost is considerably high.
To solve the above problems, it is an object of the present invention to provide wallpaper for shielding electromagnetic waves, which can effectively shield external electromagnetic waves, and which can exhibit the effect of preventing static electricity, by coating a coating composition which is composed of at least one material selected from the group consisting of a conductive polymer material having inherent resistance against electromagnetic waves, conductive carbon and graphite, and additives, mixed in a predetermined mixing ratio.
It is a second object of the present invention to protect the human body against the damages due to electromagnetic wave hazard by effectively shielding external electromagnetic waves using the electromagnetic wave shielding wallpaper.
It is a third object of the present invention to simplify the manufacturing process of electromagnetic wave shielding wallpaper to ease preparation of the wallpaper, and to reduce the manufacturing cost thereof.
In addition to the foregoing objectives, the present invention is directed to prevent malfunctioning of electronic appliances, due to electromagnetic wave interference, by decorating the interior wall of homes using the electromagnetic wave shielding wallpaper.
To achieve the above objects, there is provided wallpaper for shielding electromagnetic waves, the wallpaper prepared by applying and coating onto at least one surface of raw paper a coating composition comprising, mixed in a predetermined ratio based on the total weight of the composition, 1 to 69% by weight of at least one material selected from the group consisting of a conductive polymer material with about 1% to about 100% solids by weight of the conductive polymer material, conductive carbon and graphite, 30 to 98% by weight of matrix polymer with about 1% to about 50% solids by weight of the matrix polymer, 0 to 59% by weight of a solvent and 1 to 40% by weight of additives, and then drying the resultant surface.
Here, the conductive polymer materials include polyaniline, polypyrrole, polythiophene and derivative materials thereof, alone or in combination of two or more kinds of such materials.
Preferably, the matrix polymer is at least one material selected from the group consisting of acrylic copolymer, acrylic emulsion resin, vinyl emulsion resin, acryl resin, alkyd resin and polyester resin.
Also, the raw paper may be at least one kind of paper selected from the group consisting of raw paper for underlining, raw paper for wallpapering, nonwoven fabrics, and combination paper of nonwoven fabrics and raw paper.
The nonwoven fabrics are preferably synthetic fibers based on rayon, polyester, polypropylene, polyvinyl chloride and polyethylene terephthalate.